Newly found in Caribbean:

https://www.newscientist.com/article/2286247-dolphins-spotted-trapping-fish-in-mud-ring...

"Bottlenose dolphins are clever hunters. Some work alongside human fishers, coaxing fish ashore. Others use shells to catch their food. In the Florida Keys, some use “mud rings” – and now the behaviour has been documented in the Caribbean too.

"The mud ring hunting strategy is a case of blindsiding prey. A “ring maker” dolphin circles near the ocean floor and traps fish behind a ring of mud as others lie in wait with mouths open, and lunge to catch any fish attempting to escape the mud by jumping out of the water."

Comment: just like the bubble net feeding performed by Alaskan humpbacks who blow a circle of bubbles from below and enjoy the feast inside the bubble net. Of course humpbacks and dolphins can do simple thinking analysis.